Vernon D Larson

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Reference threshold sound-pressure levels were established for a new insert earphone, the ER-3A tubephone, and for the TDH-50 earphone. In test-retest comparisons, the tubephone produced estimates of auditory threshold as reliable as the thresholds produced by the supraaural earphone. Reference thresholds were developed for the two earphones from data(More)
Several audiological tests require knowledge of the sound-pressure spectrum at the eardrum. However, microphone readings are typically made at another, more-accessible position in the auditory canal. Recordings are then "adjusted" to the plane of the eardrum via mathematical models of the ear canal and eardrum. As bandwidths of audiological instruments have(More)
Two clinical word discrimination tests, the Northwestern University Auditory Test No. 6 (NU-6) and the Modified Rhyme Test (MRT), were examined for internal consistency and for split-half reliability under varying primary-to-secondary ratios (P:S) in normal hearers. Although the statistical analysis indicated that half-lists could be used reliably for both(More)
OBJECTIVE Subjective measures of performance were assessed on three different hearing aid circuits as part of a large clinical trial. These measurements included the Profile of Hearing Aid Performance and a subjective ranking of individual preference. DESIGN A multi-center, double-masked clinical trial of hearing aids was conducted at eight VA Medical(More)
OBJECTIVE Although numerous studies have demonstrated that hearing aids provide significant benefit, carefully controlled, multi-center clinical trials have not been conducted. A multi-center clinical trial was conducted to compare the efficacy of three commonly used hearing aid circuits: peak clipping, compression limiting, and wide dynamic range(More)
Probe-tube measurements of the differences in sound levels at three locations in ear canals were compared to the differences in levels measured at analogous positions in a Zwislocki coupler and a 2-cc cavity. The results support the recommendation of Sachs and Burkhard that probe tube measurements should not be made with the probe tube flush with the(More)
Ear simulators were designed to replicate acoustical characteristics of the average adult ear. Due to variability of ear-canal geometry and eardrum impedance among individuals, the possibility of any one person exhibiting such "average" characteristics--especially if that person is a child and/or has a conductive pathology--is remote. Thus, ear simulators(More)
Suppressing unstable acoustic feedback in hearing aids will first require knowledge of the open-loop transfer functions of such systems. Reported herein is a mathematical technique for simulating the open-loop transfer function of an in situ eyeglass-type hearing aid. In particular, a computer program was developed that characterized the hearing aid as a(More)
OBJECTIVE As part of a large clinical trial that compared three hearing aid circuits using several evaluation methods, judgments about quality of listening experiences were sought from all subjects. Three dimensions were examined: loudness, noise interference and overall liking (quality). DESIGN Eight Audiology units in VA Medical Centers participated.(More)
The effect of simulated high frequency hearing loss in young adult speakers was examined. Subjects were native English speakers with normal hearing sensitivity. There were three listening conditions, two filtered conditions simulating high frequency hearing losses similar to those often occurring in the geriatric population and one unfiltered, or normal(More)